RFR: 8349284: Make libExplicitAttach work on static JDK [v2]

[Jiangli Zhou]

> This is similar to https://github.com/openjdk/jdk/pull/23431 change. It removes libjvm.so as a recorded dependency for libExplicitAttach.so by not explicitly link libExplicitAttach.so with libjvm.so at build time. To do that, it also changes libExplicitAttach.c to dynamically lookup the JNI_GetCreatedJavaVMs symbol then invokes the function using the obtained address. The change makes the test to work on both regular 'jdk' image and the 'static-jdk' image.
> 
> There are discussions in https://github.com/openjdk/jdk/pull/23431 comment thread among @dholmes-ora, @AlanBateman and myself. Based on my understanding, we are converging on the approach to fix just these few tests, and both @dholmes-ora and @AlanBateman are okay with that. So I'm sending out this PR for libExplicitAttach's fix as well.

Jiangli Zhou has updated the pull request incrementally with one additional commit since the last revision:

  Move JNI_GetCreatedJavaVMs lookup into JNI_OnLoad, to address AlanBateman's suggestion.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23500/files
  - new: https://git.openjdk.org/jdk/pull/23500/files/b68f76b2..4ee170d2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23500&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23500&range=00-01

  Stats: 43 lines in 1 file changed: 22 ins; 21 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/23500.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23500/head:pull/23500

PR: https://git.openjdk.org/jdk/pull/23500